Summary
In recent times, significant progress has been achieved in the advancement of aerospace materials for use in structural and engine applications. Alloys, including Al-based alloys, Mg-based alloys, Ti-based alloys, and Ni-based alloys, have been developed for the aerospace industry and offer exceptional advantages. The introduction of composite materials, a novel type of material, has also played a crucial role in aircrafts. Despite these advancements, current aerospace materials still encounter significant obstacles, such as inadequate mechanical properties, fretting wear, stress corrosion cracking, and corrosion. As a result, considerable research efforts have been dedicated to creating the next generation of aerospace materials that possess superior mechanical performance and corrosion resistance to enhance both performance and the overall life cycle cost. This review focuses on the following topics: (1) the necessary materials for aircraft structures and engines, (2) recent developments in aerospace materials, (3) challenges faced by current aerospace materials, and (4) future trends in the field of aerospace materials.
Overview
The rapid expansion of the aerospace sector has spurred the advancement of novel aircraft materials. This is primarily driven by the need to decrease costs through reducing weight and extending the service life of aircraft components and structures. Creating lightweight aircraft frames and engines using materials with enhanced mechanical properties can enhance fuel efficiency, increase payload, and extend flight range, resulting in a direct reduction in operating costs [1]. As a result, numerous studies have been focused on developing materials with optimized characteristics to decrease weight and improve damage tolerance, fatigue, and corrosion resistance [1].
The origins of aircraft materials can be traced back to the initial days of flight in 1903, during which the airframe was constructed from wood. However, in 1927, the use of Al-based alloys became prevalent in aircraft materials due to advancements in cladding and anodizing technologies [2]. These alloys have been the dominant choice in aerospace materials for over 80 years [1]. However, there has been a shift in this trend in recent times. According to Fig. 1, the total materials used in Boeing aircraft models have changed. The use of Al-based alloys has decreased while composites have seen a significant increase.
Criteria for Designing Aerospace Materials
The specifications for aerospace materials differ depending on the specific part being analyzed. The selection of materials for an aircraft design is based on the individual requirements of each component, such as load conditions, ease of manufacturing, geometric restrictions, environmental factors, and durability [21].
Alloys based on Artificial Intelligence (AI)
Alloys based on aluminum were the main choice for aircraft structures until the rise in utilization of composites. However, they continue to hold significance as materials for airframe structures due to their various benefits including affordability, ease of production, and lightweight properties. These Al-based alloys can undergo heat treatment and withstand considerable amounts of stress. Recent studies have focused on the advancement of 2000 and 7000 series Al-based alloys, as well as Al-Li alloys, for use in aircraft applications.
Promising materials for aircraft use
Self-sufficient materials, including self-cleaning polymers and self-repairing substances, hold promise for extensive utilization in aircrafts. In fact, self-cleaning materials can be observed in nature, such as on lotus leaves. These leaves have the ability to repel water, causing it to roll off in droplets and carry any dirt with it [118]. The mechanisms behind self-cleaning materials can be classified into two types: those that rely on the surface’s wettability, and those that use the second category.
Wear caused by fretting
The wearing down of materials, known as fretting wear, is a result of back-and-forth movement (usually less than 100 ฮผm) between two objects in contact [20,125]. This type of wear can lead to the formation of cracks on the affected surface and can decrease the lifespan of components [126]. Fretting wear is commonly observed in both aircraft structural parts and engine components, including bearing shafts, bolted connections, and blade-disc assemblies [127]. Ti-based alloys are frequently utilized to connect with other parts and are often subjected to fretting loads.
Summary and upcoming developments
The current assessment reveals considerable advancement in the evolution of both aircraft structural materials and engine materials. The specifications for the design of aircraft structural materials demand that they possess adequate mechanical properties and exhibit suitable damage tolerance in various circumstances. For several years, Al-based alloys have been the predominant material in this sector due to their well-established mechanical characteristics. The utilization of polymer matrix composites has also seen a rise.